Sphingomyelinase (SMase) cleaves sphingomyelin to produce phosphorylcholine and ceramide. The activation of SMase leads to increased production of ceramide, which acts as a lipid second messenger. There are five distinct types of SMases. Deficiency in Acid SMase (ASMase) leads to Niemann-Pick disease type A and B. BioVision’s Acid Sphingomyleinase Activity Assay Kit provides a simple and sensitive method for measuring ASMase enzymatic activity using colorimetry (OD 570 nm). In this assay, ASMase converts its substrate, sphingomyelin to phosphorylcholine and ceramide at pH 5.0; subsequently, phosphorylcholine is utilized in a series of reactions culminating in color formation from a highly specific probe. This high-throughput adaptable assay kit can detect ASMase activity as low as 3 mU/ml in a variety of samples.